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Merged
keith merged 2 commits into from
Jul 12, 2026
+166 −184
Merged

Move wasm templating to separate BUILD file #1835

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593949c
Move wasm templating to separate BUILD file
keith Jul 8, 2026
3f19275
Discard changes to swift/internal/extensions/BUILD.bazel
keith Jul 8, 2026
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200 changes: 16 additions & 184 deletions swift/internal/extensions/swift_sdks.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -52,106 +52,6 @@ swift_tools(
)
"""

# The WebAssembly repository also generates a rules_cc cc_toolchain, so its
# BUILD header needs the rules_cc toolchain loads.
_WASM_BUILD_HEADER_TEMPLATE = """\
load("@rules_cc//cc/toolchains:args.bzl", "cc_args")
load("@rules_cc//cc/toolchains:make_variable.bzl", "cc_make_variable")
load("@rules_cc//cc/toolchains:tool.bzl", "cc_tool")
load("@rules_cc//cc/toolchains:tool_map.bzl", "cc_tool_map")
load("@rules_cc//cc/toolchains:toolchain.bzl", "cc_toolchain")
load("@rules_swift//swift/toolchains:swift_toolchain.bzl", "swift_toolchain")
load("@rules_swift//swift/toolchains:swift_tools.bzl", "swift_tools")

package(default_visibility = ["//visibility:public"])

filegroup(
name = "sdk_files",
srcs = glob(["{bundle_dir}/**"]),
)

swift_tools(
name = "tools",
swift_driver = "@{toolchain_repo}//:usr/bin/swiftc",
swift_autolink_extract = "@{toolchain_repo}//:usr/bin/swift-autolink-extract",
swift_symbolgraph_extract = "@{toolchain_repo}//:usr/bin/swift-symbolgraph-extract",
additional_inputs = {compiler_inputs},
)
"""

_CC_TOOLCHAIN_TEMPLATE = """
cc_tool(
name = "clang",
src = "{clang}",
data = {clang_data},
tags = ["manual"],
)

cc_tool(
name = "ar",
src = "{ar}",
tags = ["manual"],
)

cc_tool_map(
name = "cc_tools",
tags = ["manual"],
tools = {{
"@rules_cc//cc/toolchains/actions:ar_actions": ":ar",
"@rules_cc//cc/toolchains/actions:assembly_actions": ":clang",
"@rules_cc//cc/toolchains/actions:c_compile": ":clang",
"@rules_cc//cc/toolchains/actions:cpp_compile_actions": ":clang",
"@rules_cc//cc/toolchains/actions:link_actions": ":clang",
}},
)
"""

_CC_TOOLCHAIN_FOR_TARGET_TEMPLATE = """
cc_args(
name = "cc_args_{suffix}",
actions = [
"@rules_cc//cc/toolchains/actions:compile_actions",
"@rules_cc//cc/toolchains/actions:link_actions",
],
args = {args},
)

cc_args(
name = "cc_link_args_{suffix}",
actions = [
"@rules_cc//cc/toolchains/actions:link_actions",
],
args = {link_args},
)

cc_make_variable(
name = "cc_target_triple_{suffix}",
value = "{triple}",
variable_name = "CC_TARGET_TRIPLE",
)

cc_toolchain(
name = "cc_toolchain_{suffix}",
args = [
":cc_args_{suffix}",
":cc_link_args_{suffix}",
],
compiler = "clang",
enabled_features = [
"@rules_cc//cc/toolchains/args/archiver_flags:feature",
"@rules_cc//cc/toolchains/args/libraries_to_link:feature",
"@rules_cc//cc/toolchains/args/link_flags:feature",
# Needed so `swift_binary(linkshared = True)` links a shared library
# (passes `-shared` for the dynamic_library link action).
"@rules_cc//cc/toolchains/args/shared_flag:feature",
],
make_variables = [
":cc_target_triple_{suffix}",
],
tool_map = ":cc_tools",
)
"""

def _execroot_relative_path(path):
"""Returns the execution-root-relative path for an external repository path.

Expand Down Expand Up @@ -333,100 +233,32 @@ target Android.

def _swift_wasm_sdk_impl(repository_ctx):
bundle_dir = _download_sdk_bundle(repository_ctx)
toolchain_repo = repository_ctx.attr.toolchain_repo

repo_root = "external/" + repository_ctx.name
sdk_dir = "{}/{}/{}".format(
repo_root,
bundle_dir,
"{0}/wasm32-unknown-wasip1".format(bundle_dir.removesuffix(".artifactbundle")),
)
if not repository_ctx.path(sdk_dir.removeprefix(repo_root + "/")).exists:
fail("The WebAssembly Swift SDK bundle has an unexpected layout; " +
"missing " + sdk_dir)
wasi_sdk = sdk_dir + "/WASI.sdk"
resource_dir = sdk_dir + "/swift.xctoolchain/usr/lib/swift_static"

build_content = _WASM_BUILD_HEADER_TEMPLATE.format(
bundle_dir = bundle_dir,
compiler_inputs = _build_list([
":sdk_files",
"@{}//:swift_sdk_compiler_inputs".format(toolchain_repo),
]),
toolchain_repo = toolchain_repo,
fail("The WebAssembly Swift SDK bundle has an unexpected layout; missing " + sdk_dir)

repository_ctx.template(
"BUILD.bazel",
repository_ctx.attr._build_template,
substitutions = {
"{bundle_dir}": bundle_dir,
"{sdk_dir}": sdk_dir,
"{swift_version}": repository_ctx.attr.swift_version,
"{toolchain_repo}": repository_ctx.attr.toolchain_repo,
},
)

build_content += _SWIFT_TOOLCHAIN_TEMPLATE.format(
arch = "wasm32",
copts = _build_list([
"-resource-dir",
resource_dir,
]),
features = _build_list([
"swift.module_map_no_private_headers",
"swift.no_embed_debug_module",
# wasm-ld cannot alias a renamed entry point back to the symbol
# that wasi-libc's startup code expects.
"swift.no_entry_point_rename",
"swift.use_autolink_extract",
]),
linker_inputs = _build_list([":sdk_files"]),
# The runtime objects and libraries that `swiftc` would add when
# linking a static executable for WASI; see
# `swift_static/wasi/static-executable-args.lnk` in the SDK.
linkopts = _build_list([
"{}/wasi/wasm32/swiftrt.o".format(resource_dir),
"-L{}/wasi".format(resource_dir),
"-lc++",
"-lc++abi",
"-lswiftSwiftOnoneSupport",
"-ldl",
"-lm",
"-lwasi-emulated-mman",
"-lwasi-emulated-signal",
"-lwasi-emulated-process-clocks",
# The Swift driver always passes these bases to wasm-ld.
# `--table-base=4096` in particular is required: without it,
# optimized (`-O`) generic-metadata instantiation reads out of
# bounds at runtime (`-Onone` happens to tolerate the default).
"-Wl,--global-base=4096",
"-Wl,--table-base=4096",
]),
os = "wasi",
sdkroot = wasi_sdk,
suffix = "wasm32",
swift_version = repository_ctx.attr.swift_version,
)

build_content += _CC_TOOLCHAIN_TEMPLATE.format(
ar = "@{}//:usr/bin/llvm-ar".format(toolchain_repo),
clang = "@{}//:usr/bin/clang".format(toolchain_repo),
clang_data = _build_list([
":sdk_files",
"@{}//:swift_sdk_linker_inputs".format(toolchain_repo),
]),
)

build_content += _CC_TOOLCHAIN_FOR_TARGET_TEMPLATE.format(
args = _build_list([
"--target=wasm32-unknown-wasip1",
"--sysroot=" + wasi_sdk,
]),
# The Swift SDK's clang resource directory provides the compiler
# builtins (libclang_rt) for wasm32, which the host toolchain's own
# resource directory does not include.
link_args = _build_list([
"-resource-dir",
resource_dir + "/clang",
]),
suffix = "wasm32",
triple = "wasm32-unknown-wasip1",
)

repository_ctx.file("BUILD.bazel", build_content)

swift_wasm_sdk_repository = repository_rule(
attrs = _common_attrs(),
attrs = _common_attrs() | {
"_build_template": attr.label(
default = "//swift/internal/extensions:wasmsdk.BUILD",
),
},
doc = """\
Downloads the WebAssembly Swift SDK artifact bundle and defines Swift and C++
toolchains that target `wasm32-unknown-wasip1` using a standalone host
Expand Down
150 changes: 150 additions & 0 deletions swift/internal/extensions/wasmsdk.BUILD
View file
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Original file line number Diff line number Diff line change
@@ -0,0 +1,150 @@
load("@rules_cc//cc/toolchains:args.bzl", "cc_args")
load("@rules_cc//cc/toolchains:make_variable.bzl", "cc_make_variable")
load("@rules_cc//cc/toolchains:tool.bzl", "cc_tool")
load("@rules_cc//cc/toolchains:tool_map.bzl", "cc_tool_map")
load("@rules_cc//cc/toolchains:toolchain.bzl", "cc_toolchain")
load("@rules_swift//swift/toolchains:swift_toolchain.bzl", "swift_toolchain")
load("@rules_swift//swift/toolchains:swift_tools.bzl", "swift_tools")

_RESOURCE_DIR = "{sdk_dir}/swift.xctoolchain/usr/lib/swift_static"

_WASI_SDK = "{sdk_dir}/WASI.sdk"

filegroup(
name = "sdk_files",
srcs = glob(["{bundle_dir}/**"]),
)

swift_tools(
name = "tools",
additional_inputs = [
":sdk_files",
"@{toolchain_repo}//:swift_sdk_compiler_inputs",
],
swift_autolink_extract = "@{toolchain_repo}//:usr/bin/swift-autolink-extract",
swift_driver = "@{toolchain_repo}//:usr/bin/swiftc",
swift_symbolgraph_extract = "@{toolchain_repo}//:usr/bin/swift-symbolgraph-extract",
)

swift_toolchain(
name = "swift_toolchain_wasm32",
arch = "wasm32",
copts = [
"-resource-dir",
_RESOURCE_DIR,
],
features = [
"swift.module_map_no_private_headers",
"swift.no_embed_debug_module",
# wasm-ld cannot alias a renamed entry point back to the symbol
# that wasi-libc's startup code expects.
"swift.no_entry_point_rename",
"swift.use_autolink_extract",
],
linker_inputs = [":sdk_files"],
# The runtime objects and libraries that `swiftc` would add when linking a
# static executable for WASI; see `swift_static/wasi/static-executable-args.lnk`
# in the SDK.
linkopts = [
_RESOURCE_DIR + "/wasi/wasm32/swiftrt.o",
"-L" + _RESOURCE_DIR + "/wasi",
"-lc++",
"-lc++abi",
"-lswiftSwiftOnoneSupport",
"-ldl",
"-lm",
"-lwasi-emulated-mman",
"-lwasi-emulated-signal",
"-lwasi-emulated-process-clocks",
# The Swift driver always passes these bases to wasm-ld.
# `--table-base=4096` in particular is required: without it, optimized
# (`-O`) generic-metadata instantiation reads out of bounds at runtime
# (`-Onone` happens to tolerate the default).
"-Wl,--global-base=4096",
"-Wl,--table-base=4096",
],
os = "wasi",
parsed_version = "{swift_version}",
sdkroot = _WASI_SDK,
swift_tools = ":tools",
version_file = ".swift-version",
)

cc_tool(
name = "clang",
src = "@{toolchain_repo}//:usr/bin/clang",
data = [
":sdk_files",
"@{toolchain_repo}//:swift_sdk_linker_inputs",
],
tags = ["manual"],
)

cc_tool(
name = "ar",
src = "@{toolchain_repo}//:usr/bin/llvm-ar",
tags = ["manual"],
)

cc_tool_map(
name = "cc_tools",
tags = ["manual"],
tools = {
"@rules_cc//cc/toolchains/actions:ar_actions": ":ar",
"@rules_cc//cc/toolchains/actions:assembly_actions": ":clang",
"@rules_cc//cc/toolchains/actions:c_compile": ":clang",
"@rules_cc//cc/toolchains/actions:cpp_compile_actions": ":clang",
"@rules_cc//cc/toolchains/actions:link_actions": ":clang",
},
)

cc_args(
name = "cc_args_wasm32",
actions = [
"@rules_cc//cc/toolchains/actions:compile_actions",
"@rules_cc//cc/toolchains/actions:link_actions",
],
args = [
"--target=wasm32-unknown-wasip1",
"--sysroot=" + _WASI_SDK,
],
)

cc_args(
name = "cc_link_args_wasm32",
actions = [
"@rules_cc//cc/toolchains/actions:link_actions",
],
# The Swift SDK's clang resource directory provides the compiler builtins
# (libclang_rt) for wasm32, which the host toolchain's own resource
# directory does not include.
args = [
"-resource-dir",
_RESOURCE_DIR + "/clang",
],
)

cc_make_variable(
name = "cc_target_triple_wasm32",
value = "wasm32-unknown-wasip1",
variable_name = "CC_TARGET_TRIPLE",
)

cc_toolchain(
name = "cc_toolchain_wasm32",
args = [
":cc_args_wasm32",
":cc_link_args_wasm32",
],
compiler = "clang",
enabled_features = [
"@rules_cc//cc/toolchains/args/archiver_flags:feature",
"@rules_cc//cc/toolchains/args/libraries_to_link:feature",
"@rules_cc//cc/toolchains/args/link_flags:feature",
# Needed so `swift_binary(linkshared = True)` links a shared library
# (passes `-shared` for the dynamic_library link action).
"@rules_cc//cc/toolchains/args/shared_flag:feature",
],
make_variables = [":cc_target_triple_wasm32"],
tool_map = ":cc_tools",
)
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